Wow, Geomamma, that sounds tough! I hope you get some down time to recharge and just be in a quiet space. I find after one of "those" days I need to be out of the house and walking!
We don't have it everyday about everything with DS about to turn 5, instead we get it in clusters usually around his half or full birthday or around times of change. And then it's similar in terms of testing things that are house rules or are obviously going to be met with a negative reaction. What's been important for us is to keep reinforcing what will not be tolerated while trying to point out when he does the right thing. But I have to say my ability to handle often has a lot more to do with me than him. Especially because they all have that way of knowing what gets you the most. So besides offering sympathy and a recommendation for restoring your own sanity, when you say ALWAYS pushing do you mean that literally or can you pinpoint some patterns, hungry, bored, changing from one activity to another? If it literally is ALWAYS then perhaps the nurtured heart book that lots here recommend might help.
Hang in there!
DeHe
